Temporal Stability of Spatially Measured Soil Matric Potential Probability Density Function

Abstract

those fields. Both of these techniques, however, require more observations than are practical for most field man-Estimation of mean water status in a field is crucial to effective agers. Efforts have been made to characterize fields irrigation water management. Problems encountered with the estimation of mean field soil water status may be attributed to spatial variabil-from fewer observations. The application of bootstrapity of soil physical properties. Several investigators have shown tempo-ping techniques (Dane et al., 1986) has been used to ral stability of spatial patterns of field measured soil water content, estimate the minimum number of observations necesbut temporal stability of field measured soil matric potential ( m ), a sary for the reliable estimation of soil parameters in a measure of soil water status more appropriate for irrigation schedulvariable field. ing, has not previously been reported to last for more than a few A number of studies (Ottoni, 1984;Vachaud et al., days within one irrigation cycle. This study investigated the temporal 1985; Kachanoski and de Jong, 1988; van Wesenbeeck stability of spatial patterns of m both within and between sequential and Kachanoski, 1988; Jaynes and Hunsaker, 1989; Gooirrigation cycles. Sixty locations in a 1-ha field were outfitted with a vaerts and Chiang, 1993; Chen et al., 1995) have shown 1-m neutron probe access tube and three tensiometers placed at that, although soil water content varies with time and 0.15-, 0.3-, and 0.5-m depths. The observations obtained from 14 d with location in the field, the pattern of spatial variabilof soil water content measurements and 46 d of m measurements within eight irrigation cycles were analyzed with Spearman's rank ity does not change with time when the observations correlation coefficients and a relative differencing technique. Theare ranked according to the magnitude of soil water results showed temporally stable soil water content spatial patterns content or scaled against the field mean soil water conand also indicated temporally stable m spatial patterns if assumptions tent. This phenomenon has been termed temporal stabilof full soil wetting at the beginning of the cycle and uniform evapoity. The covariants of significance in these cases were transpiration among locations were satisfied. Several locations in the determined to be primarily soil texture and topography. field estimated the field mean m to within 10% within a given rangeThe dependence of water content upon soil texture has of potentials, and a few estimated the field mean to within 20% across also been used to locate textural boundaries in a field the entire range of potentials tested. Other locations estimated the from measurements of soil water content along a tranlower and higher percentiles of m with similar accuracy. sect in an irrigated field soil (Hendrickx et al., 1986).Although temporal stability has been demonstrated for soil water contents, it has not been shown for m . R.S. Van Pelt, USDA-ARS Plant Stress and Water Conservation eters...

Irrigation management of Romaine lettuce in Histosols at two spatial scales: water, energy, leaching and yield impacts

“…First, the uniformity of applied water may vary from 40 to 95% depending on the irrigation system used [4], then most likely not corresponding to local plant needs within the field [5] and provoking variable infiltration patterns [6]. Second, once applied to the soil, the main parameters influencing water supply to the crop are the soil physical properties like the water desorption curve, the hydraulic conductivity, soil available water, all of which are spatially dependent.…”

“…Such system can rely on water content or water potential probes measurements. As already mentioned, even with a uniform water application, plant uptake and topography, soil water potential may present an important variability due to spatial structure of unsaturated and saturated hydraulic conductivity, of pores and particle size distribution [10,11] and of soil structure [4,11,12]. In organic soils, a large variability in organic horizon depths and available water of organic horizons has been reported [13].…”

Spatial and temporal patterns of soil water content in an agroecological production system

“…Measuring SWC at these points would allow for estimating the mean of the SWC and the magnitude of its variance. Sensors located at these strategic points could be used for managing the soil water (Van Pelt and Wierenga, 2001;Starr, 2005).…”

Soil moisture temporal stability analysis for typical hilly and gully re-vegetated catchment in the Loess Plateau, China

“…Information on temporal stability has also found multiple applications, such as identifying representative locations, optimizing monitoring schemes, filling in missing data, scaling soil moisture content, improving the performance of hydrological models, and delineating water management zones (Wang 2014). Optimizing the sampling strategy for the sake of reducing the level of uncertainty in the estimation of soil moisture distribution is not only beneficial to the determination and construction of efficient networks of stations (Van Pelt and Wierenga 2001;Martinez-Fernandez and Ceballos 2003), but could also be effectively combined with remote sensing to improve the precision of soil moisture estimation as well as to calibrate and validate the confidence degree (Mohanty and Skaggs 2001;Jacobs et al 2004). Due to the wide application of the temporal stability concept and approach based on the probability density function of soil moisture under many different climatic conditions, Brocca et al (2009Brocca et al ( , 2010 systemically summarized the characteristics of the temporal stability of soil moisture and its influential factors, including topography, precipitation, and vegetation in addition to soil texture (Grayson and Western 1998;Mohanty and Skaggs 2001).…”